I purchased a sofa bed for my spare room from DFS. I wanted one that became more or less a full size double bed (4'6"), but as I already had two nice bedside tables and limited space, I wanted one that did not have space taken with arms when it was a sofa. Got one in DFS which serves perfectly. I wanted it more as a bed than a sofa, so it was the ease of use and comfort as a bed that was my priority.
This just pulls forward to open up, I do use a good 'topper; on it and it is very comfortable.
You need to think of your space, I needed a bed that pulled forward, my daughter has one in her spare room that I use when I am there, that needs to open sideways. Hers is from Ikea and has space in it to store her bedding,.
Work out what you need, space you have, whether it is more important as a bed or a sofa and how much money you wish to spend.